Electric musical instrument



Dec. 4, 1951 B. w. VAN INGEN SCHENAU 2,577,493

ELECTRIC MUSICAL INSTRUMENT 2 SHEETS SHEET 1 Filed July 20, 1946 66HENAU ay% %i 7 Aa NT Dec. 4, 1951 B. w. VAN INGEN SCHENAU 7 ELECTRIC MUSICAL INSTRUMENT Filed July 20, 1946 '2 SHEETS-SHEET 2 "fifR/VA/FDUS W/ZLZM m/w/vmv- SCHENAU AGENT Patented Dec. 4, 1951 2,577,493 ELECTRIC MUSICAL INSTRUMENT Bernardus Willem van Ingen Schcnau, Eindhoven, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford,

Conn., as trustee Application July 20, 1946, Serial No. 685,197 In the Netherlands December 23, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires December 23, 1963 This invention relates to an electric musical instrument in which the tones are produced by oscillators made operative and inoperative by means of keys, the frequency of each tone being determined by an LC-circuit.

Instruments of this kind are known, such as electric organs, which are equipped, for example, with 96 oscillators. Although these are already materially less expensive and in addition more practical than real pipe organs, there is nevertheless the drawback that they are too voluminous and too heavy to permit an easy displacement while the cost for private persons is. as a rule. too high.

The present invention purports to construct a similar instrument which can be easily carried by one person and which is in addition very inexpensive, while the reproduction approaches that of a normal church organ both with regard to volume and quality.

It is known that the various tones in an oscillator may be obtained by that one of the elements, for example the capacity of the LC-circuit, is varied in value, which may be efiected by switching on and off condensers.

The instrument according to the invention, wherein the latter principle is used, exhibits the characteristic that only such a number of oscillators is available as tones must be capable of being struck simultaneously. Consequently, the

This canother oscillators are coupled to several keys, as

a rule to most keys. Furthermore, on striking one of the keys there is always only one of the oscillators made operative while on striking a second key simultaneously with the first, a second oscillator is influenced, on Striking three keys the third oscillator, etc.

The instrument according to the invention may be of a very compact construction and have a 3 Claims. (Cl. 841.19)'

ing to the invention in which are, for example, only two oscillators and which can be used with a small pipe organ or harmonium.

The above-mentioned inventive idea may be worked out more fully as follows. For example, the instrument will be so constructed that in the position in which no keys are struck, series-connections of switches are connected in parallel with the mutually identical inductances of the LC-circuits of all the oscillators, condensers being switched between the corresponding points of each switch, hence for example the fixed contact points and the connecting lead, common to all the oscillators, between the last switch and the inductance. condensers of the various oscillatory circuits are identical to one another and the corresponding switche are connected to one and the same key. By the term corresponding condensers is understood the condensers which have one of their contact points, for example, between the first and the second switch, as viewed from the oscillator. Similarly, the term corresponding switches is understood to mean the first, the second and the third switch respectively in each oscillatory circult. Furthermore, the construction is such that.

when one key is operated, the moving contact piece of all the switches of this key but for one is connected to the fixed contact piece of every next switch of this key. On striking a key it is thus possible to make a definite oscillator operative by means of one of the switches associated with this key and also to connect the other oscillators to the switches of the next key by means of the other switches belonging to the said key.

These oscillators are thus kept in readiness to be made operative when pushing one of the next keys. Since we have started from the assumption that always only a limited number of keys need be struck simultaneously, it is evident that with the same limited number of oscillators any desired combination of the corresponding number of tones is possible in the above-described manner.

At least, in order to economize in the number of condensers required, it is advisable that the keys in the range that is least used, i. e. for example the range of low tones, should be coupled to less oscillators than in the other range. This may be carried out in steps, i. e. for the highest tones the keys may be connected to all the oscillators, underneath to one less, still lower again to one less, and at last for the lowest tones to only a single oscillator. Consequently, in the last-mentioned case only one of the-oscillators is In this case the corresponding connected to all the keys whereas the other oscillators are coupled to several keys, substantially to most-keys:

In order that the invention may bermore:clearlyunderstood and readily carried into efiect, it will Fig. 2 with one, two and three keyszstruck;and;

their operation.

At last, Fig. 6 shows diagrammaticallya simplisfied circuit of a key-board.

Fig. 1 shows a simple known circuit of an oscil lator having an LC-circuit which is constituted by an inductance L and'a condenser Cv. The points-I and-2 are further connected toanameplifier and a reproduction .devicee C, isthegrid condenser and R1; the leakageeresistancee R2,; serves ,to. givethe tone-,produceda goodsinusoidal shape-and must have a high-value;(fonexamplee 2. megohmsy. At'last,'L1- isrthe=feedback=.coil,a. wheniCv -is.- varied, different tones are produced.

Thisevariab'le condenser. is in practice replaced:

by; several, capacities, for which purpose points.

31 and 4: are connected to a circuit shown. in

present instance 23,- 24 and ;25,are-connected, via

the condensers Ste,- 3 I eand 32e, to; the connect-1 ing lead I3; cornmonto allthe oscillators; of the:

lastswitch 2.6- via point ;-to .the inductance; The; corresponding; switches; of; the; various oscillators:

are mounted .onthe same key; fonexampleon I -I These 1 keys; are. ofi insulating; material, so that.

there is no :electriccontact I between the: switches;

The-keyed I,- ,I 2, I3;. I 4-; I 5: anddtsmaybeamoved:

um and down :by; means of levers" (not;- shown 3 which". are connected; tothe. key-board; of; themusicalrinstrumentr. Ifj'aikeyyis notv-struckrit is in theypositionof rest :such,;;for: example, as I I 5 Ita; :key is: struck 'it' goes:up:as:shown;at-; I4. In: thiszcaseithe. SWitChGSfflTGfl-iftfidi at'theipointsgi 1; since; they? are.;:secured-;to:- the keys.-: so: as.- to: be

pivoted 12.1}? the points 28 Asican be ;seen;in the.

drawing,ithe;m0ving 'contactsrof all switches but for ronea, have-contacted? with the fixed; contacts;

29: of the: next; switch :of this, key: 'At last, this:- figure IShOWSIithe groupsxofz:condensersas0, 3|; 32: 33 31 and-: In eachof these-groups-the 100117" densers,-1which;are further: indicated by; a; b,-;c, d" and e, are identical to one another, butzfromr group torgroup. they are difierent. In gr0upi 3fi theacondensersiarezvariable, forrexample-realized'r as trimmers; and-serveto beablezto tunepthe:

instrument.

The" operation of; the." instrument .1 0m striking; 0116.201? morerkeys will nowbe further explained: withreference to EigssB, ,4.-and 5."

Fig; 3 shows: the. circuit: of '3 Fig-.g. 2 v of which; 1 however wonlythe key I3Jtogether with thetgrOup: of :condensers 32 giSiiShOWIl. and iin,which: this;.key;

4 the line 40 is interrupted. Now, the condensers in the LC-circuit of this oscillator can operate and. also determine the frequency; of; the tone produced. The condensers cooperating for this purpose are: 3211 and the condensers 30a and 3111 which are here not shown (see Fig. 2 and the shorts'dashelineiin Fig. 3). The other oscillators remain short-circuited since the switch which at first short-circuited O1, now through-connects 0'2 and the'switchwhich at first through-connectedQz', now connects O3 to one of the switches of the next key, etc. (long dash-line, long-short dashline, long-short-short dashlines in Fig. 3). What wasdescribed for key I3 also applies to any other. key, so. that 01 is always made operative.

In.Fig.-.4,. the two keys I2 and I5 are shown in the struck position with the two groups of condensers 3I and 34. As before, 01 oscillates with the condensers 39a1and 3m in the LC-circuitrdue to. which it produces a tone-.higherthan that in-thecaseof Fig. 3. Now, however, bythe, key; I5in;cooperation withthe key earns $110111: circuit of 02-, also is s eliminated (long dashli'neX which oscillates with the. condensers 38b, 3.I b;-. 32a, 33a; and 34a in the LC-circuit. Since. the condensers of each group are identicaLtopner, another: and hence:3IJb=3i3a and 3Ib=3Ict the. frequency of :thistone is lower than the previous. one. Theosci-llators 02, 0-4 and Gears-invariably short-'circuited (see: long-short and. longeshort-r short dash-lines). Consequently,,when a1. sec.,--- 0nd key. beside the first is struck, oziisalways; made operative. and" I5 in the struck position withzthezcorresponding groups'of condensers 3B; 32tandi34r. O1. oscillates through 3Ga=andO2 through-30b;.;3;Ia-1 and 32a (short and long dash-lines). Bymeans:

of key i 5 cooperation with the othertwo'keys:

II and I3, the short circuit of osci-llator: Oasis; also eliminated (see long-short dash line) i which oscillator '03 then produces a tone pitch of'which'."

isdetermined by the condensers 33b; .3 Ib", 32b;

33a and' 34a; It is observedthat} when theakeys' I3 alone is struck (Fig; 3) O1 produceszatonez' which is determined by the condensers so e! a and-32a. When'this 'key-isstruck simultaneously with key I! i (Fig. 5), O2'is setthereby into oscil lation, with the condnserstflb; Slitand' 32tt;

Since wai -36b, this key; although difirent 'oscil lators' and different condensers are made opera tive,- produces in either case'thesame tonesuclf as=it shouldbe. v

Gonsequentlyg if at first key" I3 and subse=- quentlykey I I isstruck-ythe same=-tone=is=repro-- duced'at firstby Oi"andsubsequentW-by Oz: If,

at last; key I2 is'a'lso'struck; O3 reproduces the? same-tone via' the'condensers 30c; 3Ib" and saw and 02 produces 'a' tone via 30b and 3 Ia.

It-is=evidnt that" the c0ndensers38 must have suchwalues that thehighest tone that is desired toproduce is determined by them; For thispur= pose' thecondensers must have a great accuracyand can, as previously mentioned, be realized as trimmers, in order to be'able' to-tune the instruis inzthesstrnck positionz. The switchesrZlatesupl so that the short-circuit of the oscillator 01' via thestone isi'already determined by the sum. of'one'; 1' Off, the condensers: 30 with .one. or; more i of: the? following, eachiof which:constitutes 101113 azsma'll portiomofithem. The; advantage;- particnlarhrf:

resides in'the fact that for these condensers use Fig. 5 shows three.;keys. I.I,,l3:-

may be made of ordinary factory condensers which are allowed to exhibit differences of 5%.

At least, Fig. 6 is a diagrammatic view of a whole key-board. In this case the keys 4| are indicated by single lines. Since, as a rule, of the keys for the lower tones a smaller number is struck simultaneously, it suffices in practice to connect these keys to less oscillators. This may be effected in steps, as can be seen from Fig. 6, so that at the left of the point 52 only four, at the left of 43 only three, at the left of 44 only two, and at the left of 45 only one oscillator can be set into oscillation at a time. This may be extended or restricted as desired. The advantage is that a smaller number of condensers is required. It is evident that in this case only one of the oscillators is connected to all the keys and the other oscillators are connected to most keys. If it is desired to produce two tones simultaneously also in the lowest range, two of the oscillators must be coupled to all the keys.

It is evident that instead of the condensers several inductances may be switched into the circuit, the constant inductances in this case having to be replaced by constant capacities.

In addition to the circuits shown, other circuits may occur in the instrument, for example for frequency doubling and the like for the stops of an organ or particular circuits to produce a piano-tone.

What I claim is:

1. In an electrical musical instrument playable by keys and adapted to generate simultaneously a predetermined number of tones, the combination comprising a plurality of electronic oscillators whose number corresponds to said predetermined number, each oscillator being provided with a like inductor forming one element in a parallel-resonant circuit, the inductors of said oscillators having one end thereof interconnected, a like plurality of identical switching systems each constituted by a chain of seriallyconnected switches having a fixed contact and a movable contact normally engaging said fixed contact, the movable contact of each switch in the chain being connected to the fixed contact in the succeeding switch, the fixed contact of the first switch in the chain being connected to the other end of a respective inductor and the movable contact of the last switch in the chain being connected to the interconnection of said inductors, a multiplicity of identical groups of condensers, said multiplicity being equal in number to the number of switches constituting said chain, the condensers forming each group having substantially different values and being equal in number to said predetermined number, the condensers of the different groups having progressively different values, the corresponding condensers of said groups being connected between respective fixed contacts in the chain of switches in one of said systems and said interconnection, and means operatively coupling corresponding switches of said systems to a respective key of said instrument, the corresponding switches being banked whereby the operation of said key caused the movable contacts of each of said switches to engage the fixed contact of the succeeding switch in the bank excepting for the movable contact of the last switch which is disengaged.

2. An electrical musical instrument adapted to generate simultaneously a predetermined number of tones comprising a plurality of oscillators whose :number corresponds to said predetermined number, a series of playable keys, switching means electrically coupling said keys to said oscillators and so connected that on striking any one key in said series always the same one of said oscillators is activated and on simultaneously striking the succeeding key in said series always the same one and the same another of said oscillators is activated, and a plurality of frequency determining elements connected to said switching means for insertion in said oscillators when said keys are struck, said elements being arranged to produce a distinct oscillatory tone for each key in said series.

3. The combination, as set forth in claim 1, wherein the predetermined number of tones which the instrument is adapted to generate includes a range of higher tones and a range of lower tones and wherein, in order to reduce the number of circuit components entailed for the ity thereof are connected with each of the lower lower tones, fewer of the oscillators in the pluraltone keys than for the higher tone keys.

BERNARDUS W. VAN INGEN SCHENAU.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,045,172 Yungblut June 23, 1936 2,245,337 Hammond June 10, 1941 2,254,284 Hanert Sept. 2, 1941 2,274,199 Hammond Feb. 24, 1942 2,295,524 Hanert Sept. 8, 1942 2,301,871 Hanert Nov. 10, 1942 2,357,191 Hanert Aug. 29, 1944 FOREIGN PATENTS Number Country Date 566,815 Germany Dec. 8, 1932 

